1 . <Field of the Invention>
The present invention relates to a fastening pin for a rigid member to be driven and a manufacturing method thereof. More specifically, the present invention relates to a fastening pin capable of fastening a thin steel sheet such as a bracket or a plate into the rigid member such as a concrete or a metal steel.
2. <Related Art>
In a construction such as a building or in a civil engineering construction such as a bridge or a tunnel, a fastening member is driven by a tool using a driving source such as a compressed air, a combustion gas or a gunpowder, in order to fasten a thin steel sheet such as a bracket or a plate into a rigid member such as a concrete or a metal steel.
Patent Documents 1 to 3 disclose, as the fastening member, a concrete pin in which a head side of a shaft part is formed to have a large diameter and a leading end side thereof is formed to have a small diameter.
Patent Document 1: EP2085624
Patent Document 1: U.S. Pat. No. 6,171,042
Patent Document 1: JP-A-2008-051153
However, since a rigid concrete is utilized in a high strength construction and the conventional concrete pin is provided at its middle part with a large step or a taper angle of its head part side is set too large, a driving resistance increases and thus a portion below the head part is liable to be flexed. As a result, a poor driving is frequently occurred. Further, in the recent, strength of the construction is gradually increased, a rebuilding construction of a concrete building tends to be increased, and the strength of the concrete is increased due to material age thereof. Accordingly, a pin which can be driven into more rigid member is strongly demanded. Of course, when a pin is driven into a rigid member having strength over substantially 60 N/mm2, a tool with sufficient power is necessary. In this case, from the viewpoint of workability due to a size of a driving tool itself, it is necessary to reduce a penetration resistance for the rigid member when being driven and to retain the fastening force (retaining force of the pin) for the rigid member after being driven.
When the concrete pin is driven into the rigid member, the pin is driven and penetrated substantially perpendicular to the rigid member. However, since the rigid member is used as a member to be driven, the shaft part and the under-head part directly below the head part are required for high strength. If the strength is insufficient, the shaft part is liable to be flexed or the under-head part is liable to be bent, thereby hindering a fastening operation. If a pin with a step is to be employed for corresponding to very rigid concrete such as ultra high strength concrete which is recently developed and practically used, it is necessary to increase a shaft diameter to improve the strength. As a result, the penetration resistance is increased and thus a tool with sufficient power is necessary.
Further, it is not easy to manufacture a concrete pin in which entire shaft part is formed in a taper shape or the under-head part is formed in a rounded shape. Also, a pin having a large shaft diameter can afford a high strength but this pin is expensive. When a fastening pin having a large shaft diameter is used in order to afford high strength, an outer diameter of a metal rod member used as a material also becomes large. Accordingly, there is a problem that the manufacturing cost becomes expensive.